Lenovo Trim Yellow rectangular power adapter

Solution 1:

Quick explanation

This image seems to point to the internal plates being connected internally, with the outside as a 0v line

In depth explanation

As the two plates are connected, which plate is on which side shouldn't matter, as they are directly connected to each other.

This can best be explained with the following diagram:

Black is 0v, red is 20v, blue is the data pin, if you flip the diagram 180 degrees it is the same:

So no matter which way up the connector is, the inside plates are at 20v, the outside shell is at 0v, making the connector still work, so the laptop can take its power between either of the inside plates and the shell and always get 20v with the same polarity.

Side note - Data pin

The resistance between the data pin and ground indicates the power rating.

|45 W |120 Ω | 
|65 W |280 Ω | 
|90 W |550 Ω | 
|135W |1 kΩ. | 
|170W |1.9 kΩ|

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